Dr. Madsen has demonstrated a commitment to a career as a clinician scientist and brings a unique perspective to clinical research with her background in business and product development. In the rich research environment of the University of California, the candidate will be mentored by Dr. Pat Crawford of DC Berkeley, an internationally-recognized specialist in community-based research in childhood obesity, and Dr. Michael Cabana, the Director of the Division of General Pediatrics at UCSF. With their guidance, Dr. Madsen will conduct a randomized controlled trial to determine the effect of an existing multifaceted after-school program on BMI and fitness in children at greatest risk for obesity. In the proposed research, sixty-four 3rd. to 5th. grade minority students will be randomized to participate in the after-school program or to control status. In addition, Dr. Madsen will carry out qualitative research regarding barriers to enrollment and active participation in after-school programs that promote physical activity. Results from the proposed research will provide preliminary data for and inform the design of a large-scale study, to take place in the next 5-7 years, of the efficacy of an after-school program to reduce pediatric obesity. This award will allow Dr. Madsen to gain the skills necessary for an academic career in community-based research to prevent and treat pediatric obesity and weight-related health disparities. Relevance: Given the disproportionate prevalence of obesity in minority communities, weight-related health disparities will increase if obesity is not prevented and treated in minority children. The after-school setting is an important place to intervene to increase children's healthy behaviors, and evaluating existing after-school programs may identify cost-effective solutions to the obesity epidemic. The long-term goal of this project is to provide evidence to inform policy and make after-school programs available to children who are most at risk for obesity and who would otherwise have limited access to healthy after-school activities.